//     Underscore.js 1.3.3
//     (c) 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.
//     Underscore is freely distributable under the MIT license.
//     Portions of Underscore are inspired or borrowed from Prototype,
//     Oliver Steele's Functional, and John Resig's Micro-Templating.
//     For all details and documentation:
//     http://documentcloud.github.com/underscore

(function() {

    // Baseline setup
    // --------------

    // Establish the root object, `window` in the browser, or `global` on the server.
    var root = this;

    // Save the previous value of the `_` variable.
    var previousUnderscore = root._;

    // Establish the object that gets returned to break out of a loop iteration.
    var breaker = {};

    // Save bytes in the minified (but not gzipped) version:
    var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;

    // Create quick reference variables for speed access to core prototypes.
    var slice            = ArrayProto.slice,
        unshift          = ArrayProto.unshift,
        toString         = ObjProto.toString,
        hasOwnProperty   = ObjProto.hasOwnProperty;

    // All **ECMAScript 5** native function implementations that we hope to use
    // are declared here.
    var
        nativeForEach      = ArrayProto.forEach,
        nativeMap          = ArrayProto.map,
        nativeReduce       = ArrayProto.reduce,
        nativeReduceRight  = ArrayProto.reduceRight,
        nativeFilter       = ArrayProto.filter,
        nativeEvery        = ArrayProto.every,
        nativeSome         = ArrayProto.some,
        nativeIndexOf      = ArrayProto.indexOf,
        nativeLastIndexOf  = ArrayProto.lastIndexOf,
        nativeIsArray      = Array.isArray,
        nativeKeys         = Object.keys,
        nativeBind         = FuncProto.bind;

    // Create a safe reference to the Underscore object for use below.
    var _ = function(obj) { return new wrapper(obj); };

    // Export the Underscore object for **Node.js**, with
    // backwards-compatibility for the old `require()` API. If we're in
    // the browser, add `_` as a global object via a string identifier,
    // for Closure Compiler "advanced" mode.
    if (typeof exports !== 'undefined') {
        if (typeof module !== 'undefined' && module.exports) {
            exports = module.exports = _;
        }
        exports._ = _;
    } else {
        root['_'] = _;
    }

    // Current version.
    _.VERSION = '1.3.3';

    // Collection Functions
    // --------------------

    // The cornerstone, an `each` implementation, aka `forEach`.
    // Handles objects with the built-in `forEach`, arrays, and raw objects.
    // Delegates to **ECMAScript 5**'s native `forEach` if available.
    var each = _.each = _.forEach = function(obj, iterator, context) {
        if (obj == null) return;
        if (nativeForEach && obj.forEach === nativeForEach) {
            obj.forEach(iterator, context);
        } else if (obj.length === +obj.length) {
            for (var i = 0, l = obj.length; i < l; i++) {
                if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
            }
        } else {
            for (var key in obj) {
                if (_.has(obj, key)) {
                    if (iterator.call(context, obj[key], key, obj) === breaker) return;
                }
            }
        }
    };

    // Return the results of applying the iterator to each element.
    // Delegates to **ECMAScript 5**'s native `map` if available.
    _.map = _.collect = function(obj, iterator, context) {
        var results = [];
        if (obj == null) return results;
        if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
        each(obj, function(value, index, list) {
            results[results.length] = iterator.call(context, value, index, list);
        });
        if (obj.length === +obj.length) results.length = obj.length;
        return results;
    };

    // **Reduce** builds up a single result from a list of values, aka `inject`,
    // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
    _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
        var initial = arguments.length > 2;
        if (obj == null) obj = [];
        if (nativeReduce && obj.reduce === nativeReduce) {
            if (context) iterator = _.bind(iterator, context);
            return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
        }
        each(obj, function(value, index, list) {
            if (!initial) {
                memo = value;
                initial = true;
            } else {
                memo = iterator.call(context, memo, value, index, list);
            }
        });
        if (!initial) throw new TypeError('Reduce of empty array with no initial value');
        return memo;
    };

    // The right-associative version of reduce, also known as `foldr`.
    // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
    _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
        var initial = arguments.length > 2;
        if (obj == null) obj = [];
        if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
            if (context) iterator = _.bind(iterator, context);
            return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
        }
        var reversed = _.toArray(obj).reverse();
        if (context && !initial) iterator = _.bind(iterator, context);
        return initial ? _.reduce(reversed, iterator, memo, context) : _.reduce(reversed, iterator);
    };

    // Return the first value which passes a truth test. Aliased as `detect`.
    _.find = _.detect = function(obj, iterator, context) {
        var result;
        any(obj, function(value, index, list) {
            if (iterator.call(context, value, index, list)) {
                result = value;
                return true;
            }
        });
        return result;
    };

    // Return all the elements that pass a truth test.
    // Delegates to **ECMAScript 5**'s native `filter` if available.
    // Aliased as `select`.
    _.filter = _.select = function(obj, iterator, context) {
        var results = [];
        if (obj == null) return results;
        if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
        each(obj, function(value, index, list) {
            if (iterator.call(context, value, index, list)) results[results.length] = value;
        });
        return results;
    };

    // Return all the elements for which a truth test fails.
    _.reject = function(obj, iterator, context) {
        var results = [];
        if (obj == null) return results;
        each(obj, function(value, index, list) {
            if (!iterator.call(context, value, index, list)) results[results.length] = value;
        });
        return results;
    };

    // Determine whether all of the elements match a truth test.
    // Delegates to **ECMAScript 5**'s native `every` if available.
    // Aliased as `all`.
    _.every = _.all = function(obj, iterator, context) {
        var result = true;
        if (obj == null) return result;
        if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
        each(obj, function(value, index, list) {
            if (!(result = result && iterator.call(context, value, index, list))) return breaker;
        });
        return !!result;
    };

    // Determine if at least one element in the object matches a truth test.
    // Delegates to **ECMAScript 5**'s native `some` if available.
    // Aliased as `any`.
    var any = _.some = _.any = function(obj, iterator, context) {
        iterator || (iterator = _.identity);
        var result = false;
        if (obj == null) return result;
        if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
        each(obj, function(value, index, list) {
            if (result || (result = iterator.call(context, value, index, list))) return breaker;
        });
        return !!result;
    };

    // Determine if a given value is included in the array or object using `===`.
    // Aliased as `contains`.
    _.include = _.contains = function(obj, target) {
        var found = false;
        if (obj == null) return found;
        if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
        found = any(obj, function(value) {
            return value === target;
        });
        return found;
    };

    // Invoke a method (with arguments) on every item in a collection.
    _.invoke = function(obj, method) {
        var args = slice.call(arguments, 2);
        return _.map(obj, function(value) {
            return (_.isFunction(method) ? method || value : value[method]).apply(value, args);
        });
    };

    // Convenience version of a common use case of `map`: fetching a property.
    _.pluck = function(obj, key) {
        return _.map(obj, function(value){ return value[key]; });
    };

    // Return the maximum element or (element-based computation).
    _.max = function(obj, iterator, context) {
        if (!iterator && _.isArray(obj) && obj[0] === +obj[0]) return Math.max.apply(Math, obj);
        if (!iterator && _.isEmpty(obj)) return -Infinity;
        var result = {computed : -Infinity};
        each(obj, function(value, index, list) {
            var computed = iterator ? iterator.call(context, value, index, list) : value;
            computed >= result.computed && (result = {value : value, computed : computed});
        });
        return result.value;
    };

    // Return the minimum element (or element-based computation).
    _.min = function(obj, iterator, context) {
        if (!iterator && _.isArray(obj) && obj[0] === +obj[0]) return Math.min.apply(Math, obj);
        if (!iterator && _.isEmpty(obj)) return Infinity;
        var result = {computed : Infinity};
        each(obj, function(value, index, list) {
            var computed = iterator ? iterator.call(context, value, index, list) : value;
            computed < result.computed && (result = {value : value, computed : computed});
        });
        return result.value;
    };

    // Shuffle an array.
    _.shuffle = function(obj) {
        var shuffled = [], rand;
        each(obj, function(value, index, list) {
            rand = Math.floor(Math.random() * (index + 1));
            shuffled[index] = shuffled[rand];
            shuffled[rand] = value;
        });
        return shuffled;
    };

    // Sort the object's values by a criterion produced by an iterator.
    _.sortBy = function(obj, val, context) {
        var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };
        return _.pluck(_.map(obj, function(value, index, list) {
            return {
                value : value,
                criteria : iterator.call(context, value, index, list)
            };
        }).sort(function(left, right) {
                var a = left.criteria, b = right.criteria;
                if (a === void 0) return 1;
                if (b === void 0) return -1;
                return a < b ? -1 : a > b ? 1 : 0;
            }), 'value');
    };

    // Groups the object's values by a criterion. Pass either a string attribute
    // to group by, or a function that returns the criterion.
    _.groupBy = function(obj, val) {
        var result = {};
        var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };
        each(obj, function(value, index) {
            var key = iterator(value, index);
            (result[key] || (result[key] = [])).push(value);
        });
        return result;
    };

    // Use a comparator function to figure out at what index an object should
    // be inserted so as to maintain order. Uses binary search.
    _.sortedIndex = function(array, obj, iterator) {
        iterator || (iterator = _.identity);
        var low = 0, high = array.length;
        while (low < high) {
            var mid = (low + high) >> 1;
            iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
        }
        return low;
    };

    // Safely convert anything iterable into a real, live array.
    _.toArray = function(obj) {
        if (!obj)                                     return [];
        if (_.isArray(obj))                           return slice.call(obj);
        if (_.isArguments(obj))                       return slice.call(obj);
        if (obj.toArray && _.isFunction(obj.toArray)) return obj.toArray();
        return _.values(obj);
    };

    // Return the number of elements in an object.
    _.size = function(obj) {
        return _.isArray(obj) ? obj.length : _.keys(obj).length;
    };

    // Array Functions
    // ---------------

    // Get the first element of an array. Passing **n** will return the first N
    // values in the array. Aliased as `head` and `take`. The **guard** check
    // allows it to work with `_.map`.
    _.first = _.head = _.take = function(array, n, guard) {
        return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
    };

    // Returns everything but the last entry of the array. Especcialy useful on
    // the arguments object. Passing **n** will return all the values in
    // the array, excluding the last N. The **guard** check allows it to work with
    // `_.map`.
    _.initial = function(array, n, guard) {
        return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
    };

    // Get the last element of an array. Passing **n** will return the last N
    // values in the array. The **guard** check allows it to work with `_.map`.
    _.last = function(array, n, guard) {
        if ((n != null) && !guard) {
            return slice.call(array, Math.max(array.length - n, 0));
        } else {
            return array[array.length - 1];
        }
    };

    // Returns everything but the first entry of the array. Aliased as `tail`.
    // Especially useful on the arguments object. Passing an **index** will return
    // the rest of the values in the array from that index onward. The **guard**
    // check allows it to work with `_.map`.
    _.rest = _.tail = function(array, index, guard) {
        return slice.call(array, (index == null) || guard ? 1 : index);
    };

    // Trim out all falsy values from an array.
    _.compact = function(array) {
        return _.filter(array, function(value){ return !!value; });
    };

    // Return a completely flattened version of an array.
    _.flatten = function(array, shallow) {
        return _.reduce(array, function(memo, value) {
            if (_.isArray(value)) return memo.concat(shallow ? value : _.flatten(value));
            memo[memo.length] = value;
            return memo;
        }, []);
    };

    // Return a version of the array that does not contain the specified value(s).
    _.without = function(array) {
        return _.difference(array, slice.call(arguments, 1));
    };

    // Produce a duplicate-free version of the array. If the array has already
    // been sorted, you have the option of using a faster algorithm.
    // Aliased as `unique`.
    _.uniq = _.unique = function(array, isSorted, iterator) {
        var initial = iterator ? _.map(array, iterator) : array;
        var results = [];
        // The `isSorted` flag is irrelevant if the array only contains two elements.
        if (array.length < 3) isSorted = true;
        _.reduce(initial, function (memo, value, index) {
            if (isSorted ? _.last(memo) !== value || !memo.length : !_.include(memo, value)) {
                memo.push(value);
                results.push(array[index]);
            }
            return memo;
        }, []);
        return results;
    };

    // Produce an array that contains the union: each distinct element from all of
    // the passed-in arrays.
    _.union = function() {
        return _.uniq(_.flatten(arguments, true));
    };

    // Produce an array that contains every item shared between all the
    // passed-in arrays. (Aliased as "intersect" for back-compat.)
    _.intersection = _.intersect = function(array) {
        var rest = slice.call(arguments, 1);
        return _.filter(_.uniq(array), function(item) {
            return _.every(rest, function(other) {
                return _.indexOf(other, item) >= 0;
            });
        });
    };

    // Take the difference between one array and a number of other arrays.
    // Only the elements present in just the first array will remain.
    _.difference = function(array) {
        var rest = _.flatten(slice.call(arguments, 1), true);
        return _.filter(array, function(value){ return !_.include(rest, value); });
    };

    // Zip together multiple lists into a single array -- elements that share
    // an index go together.
    _.zip = function() {
        var args = slice.call(arguments);
        var length = _.max(_.pluck(args, 'length'));
        var results = new Array(length);
        for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
        return results;
    };

    // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
    // we need this function. Return the position of the first occurrence of an
    // item in an array, or -1 if the item is not included in the array.
    // Delegates to **ECMAScript 5**'s native `indexOf` if available.
    // If the array is large and already in sort order, pass `true`
    // for **isSorted** to use binary search.
    _.indexOf = function(array, item, isSorted) {
        if (array == null) return -1;
        var i, l;
        if (isSorted) {
            i = _.sortedIndex(array, item);
            return array[i] === item ? i : -1;
        }
        if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
        for (i = 0, l = array.length; i < l; i++) if (i in array && array[i] === item) return i;
        return -1;
    };

    // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
    _.lastIndexOf = function(array, item) {
        if (array == null) return -1;
        if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
        var i = array.length;
        while (i--) if (i in array && array[i] === item) return i;
        return -1;
    };

    // Generate an integer Array containing an arithmetic progression. A port of
    // the native Python `range()` function. See
    // [the Python documentation](http://docs.python.org/library/functions.html#range).
    _.range = function(start, stop, step) {
        if (arguments.length <= 1) {
            stop = start || 0;
            start = 0;
        }
        step = arguments[2] || 1;

        var len = Math.max(Math.ceil((stop - start) / step), 0);
        var idx = 0;
        var range = new Array(len);

        while(idx < len) {
            range[idx++] = start;
            start += step;
        }

        return range;
    };

    // Function (ahem) Functions
    // ------------------

    // Reusable constructor function for prototype setting.
    var ctor = function(){};

    // Create a function bound to a given object (assigning `this`, and arguments,
    // optionally). Binding with arguments is also known as `curry`.
    // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
    // We check for `func.bind` first, to fail fast when `func` is undefined.
    _.bind = function bind(func, context) {
        var bound, args;
        if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
        if (!_.isFunction(func)) throw new TypeError;
        args = slice.call(arguments, 2);
        return bound = function() {
            if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
            ctor.prototype = func.prototype;
            var self = new ctor;
            var result = func.apply(self, args.concat(slice.call(arguments)));
            if (Object(result) === result) return result;
            return self;
        };
    };

    // Bind all of an object's methods to that object. Useful for ensuring that
    // all callbacks defined on an object belong to it.
    _.bindAll = function(obj) {
        var funcs = slice.call(arguments, 1);
        if (funcs.length == 0) funcs = _.functions(obj);
        each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
        return obj;
    };

    // Memoize an expensive function by storing its results.
    _.memoize = function(func, hasher) {
        var memo = {};
        hasher || (hasher = _.identity);
        return function() {
            var key = hasher.apply(this, arguments);
            return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
        };
    };

    // Delays a function for the given number of milliseconds, and then calls
    // it with the arguments supplied.
    _.delay = function(func, wait) {
        var args = slice.call(arguments, 2);
        return setTimeout(function(){ return func.apply(null, args); }, wait);
    };

    // Defers a function, scheduling it to run after the current call stack has
    // cleared.
    _.defer = function(func) {
        return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
    };

    // Returns a function, that, when invoked, will only be triggered at most once
    // during a given window of time.
    _.throttle = function(func, wait) {
        var context, args, timeout, throttling, more, result;
        var whenDone = _.debounce(function(){ more = throttling = false; }, wait);
        return function() {
            context = this; args = arguments;
            var later = function() {
                timeout = null;
                if (more) func.apply(context, args);
                whenDone();
            };
            if (!timeout) timeout = setTimeout(later, wait);
            if (throttling) {
                more = true;
            } else {
                result = func.apply(context, args);
            }
            whenDone();
            throttling = true;
            return result;
        };
    };

    // Returns a function, that, as long as it continues to be invoked, will not
    // be triggered. The function will be called after it stops being called for
    // N milliseconds. If `immediate` is passed, trigger the function on the
    // leading edge, instead of the trailing.
    _.debounce = function(func, wait, immediate) {
        var timeout;
        return function() {
            var context = this, args = arguments;
            var later = function() {
                timeout = null;
                if (!immediate) func.apply(context, args);
            };
            if (immediate && !timeout) func.apply(context, args);
            clearTimeout(timeout);
            timeout = setTimeout(later, wait);
        };
    };

    // Returns a function that will be executed at most one time, no matter how
    // often you call it. Useful for lazy initialization.
    _.once = function(func) {
        var ran = false, memo;
        return function() {
            if (ran) return memo;
            ran = true;
            return memo = func.apply(this, arguments);
        };
    };

    // Returns the first function passed as an argument to the second,
    // allowing you to adjust arguments, run code before and after, and
    // conditionally execute the original function.
    _.wrap = function(func, wrapper) {
        return function() {
            var args = [func].concat(slice.call(arguments, 0));
            return wrapper.apply(this, args);
        };
    };

    // Returns a function that is the composition of a list of functions, each
    // consuming the return value of the function that follows.
    _.compose = function() {
        var funcs = arguments;
        return function() {
            var args = arguments;
            for (var i = funcs.length - 1; i >= 0; i--) {
                args = [funcs[i].apply(this, args)];
            }
            return args[0];
        };
    };

    // Returns a function that will only be executed after being called N times.
    _.after = function(times, func) {
        if (times <= 0) return func();
        return function() {
            if (--times < 1) { return func.apply(this, arguments); }
        };
    };

    // Object Functions
    // ----------------

    // Retrieve the names of an object's properties.
    // Delegates to **ECMAScript 5**'s native `Object.keys`
    _.keys = nativeKeys || function(obj) {
        if (obj !== Object(obj)) throw new TypeError('Invalid object');
        var keys = [];
        for (var key in obj) if (_.has(obj, key)) keys[keys.length] = key;
        return keys;
    };

    // Retrieve the values of an object's properties.
    _.values = function(obj) {
        return _.map(obj, _.identity);
    };

    // Return a sorted list of the function names available on the object.
    // Aliased as `methods`
    _.functions = _.methods = function(obj) {
        var names = [];
        for (var key in obj) {
            if (_.isFunction(obj[key])) names.push(key);
        }
        return names.sort();
    };

    // Extend a given object with all the properties in passed-in object(s).
    _.extend = function(obj) {
        each(slice.call(arguments, 1), function(source) {
            for (var prop in source) {
                obj[prop] = source[prop];
            }
        });
        return obj;
    };

    // Return a copy of the object only containing the whitelisted properties.
    _.pick = function(obj) {
        var result = {};
        each(_.flatten(slice.call(arguments, 1)), function(key) {
            if (key in obj) result[key] = obj[key];
        });
        return result;
    };

    // Fill in a given object with default properties.
    _.defaults = function(obj) {
        each(slice.call(arguments, 1), function(source) {
            for (var prop in source) {
                if (obj[prop] == null) obj[prop] = source[prop];
            }
        });
        return obj;
    };

    // Create a (shallow-cloned) duplicate of an object.
    _.clone = function(obj) {
        if (!_.isObject(obj)) return obj;
        return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
    };

    // Invokes interceptor with the obj, and then returns obj.
    // The primary purpose of this method is to "tap into" a method chain, in
    // order to perform operations on intermediate results within the chain.
    _.tap = function(obj, interceptor) {
        interceptor(obj);
        return obj;
    };

    // Internal recursive comparison function.
    function eq(a, b, stack) {
        // Identical objects are equal. `0 === -0`, but they aren't identical.
        // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.
        if (a === b) return a !== 0 || 1 / a == 1 / b;
        // A strict comparison is necessary because `null == undefined`.
        if (a == null || b == null) return a === b;
        // Unwrap any wrapped objects.
        if (a._chain) a = a._wrapped;
        if (b._chain) b = b._wrapped;
        // Invoke a custom `isEqual` method if one is provided.
        if (a.isEqual && _.isFunction(a.isEqual)) return a.isEqual(b);
        if (b.isEqual && _.isFunction(b.isEqual)) return b.isEqual(a);
        // Compare `[[Class]]` names.
        var className = toString.call(a);
        if (className != toString.call(b)) return false;
        switch (className) {
            // Strings, numbers, dates, and booleans are compared by value.
            case '[object String]':
                // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
                // equivalent to `new String("5")`.
                return a == String(b);
            case '[object Number]':
                // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
                // other numeric values.
                return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
            case '[object Date]':
            case '[object Boolean]':
                // Coerce dates and booleans to numeric primitive values. Dates are compared by their
                // millisecond representations. Note that invalid dates with millisecond representations
                // of `NaN` are not equivalent.
                return +a == +b;
            // RegExps are compared by their source patterns and flags.
            case '[object RegExp]':
                return a.source == b.source &&
                    a.global == b.global &&
                    a.multiline == b.multiline &&
                    a.ignoreCase == b.ignoreCase;
        }
        if (typeof a != 'object' || typeof b != 'object') return false;
        // Assume equality for cyclic structures. The algorithm for detecting cyclic
        // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
        var length = stack.length;
        while (length--) {
            // Linear search. Performance is inversely proportional to the number of
            // unique nested structures.
            if (stack[length] == a) return true;
        }
        // Add the first object to the stack of traversed objects.
        stack.push(a);
        var size = 0, result = true;
        // Recursively compare objects and arrays.
        if (className == '[object Array]') {
            // Compare array lengths to determine if a deep comparison is necessary.
            size = a.length;
            result = size == b.length;
            if (result) {
                // Deep compare the contents, ignoring non-numeric properties.
                while (size--) {
                    // Ensure commutative equality for sparse arrays.
                    if (!(result = size in a == size in b && eq(a[size], b[size], stack))) break;
                }
            }
        } else {
            // Objects with different constructors are not equivalent.
            if ('constructor' in a != 'constructor' in b || a.constructor != b.constructor) return false;
            // Deep compare objects.
            for (var key in a) {
                if (_.has(a, key)) {
                    // Count the expected number of properties.
                    size++;
                    // Deep compare each member.
                    if (!(result = _.has(b, key) && eq(a[key], b[key], stack))) break;
                }
            }
            // Ensure that both objects contain the same number of properties.
            if (result) {
                for (key in b) {
                    if (_.has(b, key) && !(size--)) break;
                }
                result = !size;
            }
        }
        // Remove the first object from the stack of traversed objects.
        stack.pop();
        return result;
    }

    // Perform a deep comparison to check if two objects are equal.
    _.isEqual = function(a, b) {
        return eq(a, b, []);
    };

    // Is a given array, string, or object empty?
    // An "empty" object has no enumerable own-properties.
    _.isEmpty = function(obj) {
        if (obj == null) return true;
        if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
        for (var key in obj) if (_.has(obj, key)) return false;
        return true;
    };

    // Is a given value a DOM element?
    _.isElement = function(obj) {
        return !!(obj && obj.nodeType == 1);
    };

    // Is a given value an array?
    // Delegates to ECMA5's native Array.isArray
    _.isArray = nativeIsArray || function(obj) {
        return toString.call(obj) == '[object Array]';
    };

    // Is a given variable an object?
    _.isObject = function(obj) {
        return obj === Object(obj);
    };

    // Is a given variable an arguments object?
    _.isArguments = function(obj) {
        return toString.call(obj) == '[object Arguments]';
    };
    if (!_.isArguments(arguments)) {
        _.isArguments = function(obj) {
            return !!(obj && _.has(obj, 'callee'));
        };
    }

    // Is a given value a function?
    _.isFunction = function(obj) {
        return toString.call(obj) == '[object Function]';
    };

    // Is a given value a string?
    _.isString = function(obj) {
        return toString.call(obj) == '[object String]';
    };

    // Is a given value a number?
    _.isNumber = function(obj) {
        return toString.call(obj) == '[object Number]';
    };

    // Is a given object a finite number?
    _.isFinite = function(obj) {
        return _.isNumber(obj) && isFinite(obj);
    };

    // Is the given value `NaN`?
    _.isNaN = function(obj) {
        // `NaN` is the only value for which `===` is not reflexive.
        return obj !== obj;
    };

    // Is a given value a boolean?
    _.isBoolean = function(obj) {
        return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
    };

    // Is a given value a date?
    _.isDate = function(obj) {
        return toString.call(obj) == '[object Date]';
    };

    // Is the given value a regular expression?
    _.isRegExp = function(obj) {
        return toString.call(obj) == '[object RegExp]';
    };

    // Is a given value equal to null?
    _.isNull = function(obj) {
        return obj === null;
    };

    // Is a given variable undefined?
    _.isUndefined = function(obj) {
        return obj === void 0;
    };

    // Has own property?
    _.has = function(obj, key) {
        return hasOwnProperty.call(obj, key);
    };

    // Utility Functions
    // -----------------

    // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
    // previous owner. Returns a reference to the Underscore object.
    _.noConflict = function() {
        root._ = previousUnderscore;
        return this;
    };

    // Keep the identity function around for default iterators.
    _.identity = function(value) {
        return value;
    };

    // Run a function **n** times.
    _.times = function (n, iterator, context) {
        for (var i = 0; i < n; i++) iterator.call(context, i);
    };

    // Escape a string for HTML interpolation.
    _.escape = function(string) {
        return (''+string).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#x27;').replace(/\//g,'&#x2F;');
    };

    // If the value of the named property is a function then invoke it;
    // otherwise, return it.
    _.result = function(object, property) {
        if (object == null) return null;
        var value = object[property];
        return _.isFunction(value) ? value.call(object) : value;
    };

    // Add your own custom functions to the Underscore object, ensuring that
    // they're correctly added to the OOP wrapper as well.
    _.mixin = function(obj) {
        each(_.functions(obj), function(name){
            addToWrapper(name, _[name] = obj[name]);
        });
    };

    // Generate a unique integer id (unique within the entire client session).
    // Useful for temporary DOM ids.
    var idCounter = 0;
    _.uniqueId = function(prefix) {
        var id = idCounter++;
        return prefix ? prefix + id : id;
    };

    // By default, Underscore uses ERB-style template delimiters, change the
    // following template settings to use alternative delimiters.
    _.templateSettings = {
        evaluate    : /<%([\s\S]+?)%>/g,
        interpolate : /<%=([\s\S]+?)%>/g,
        escape      : /<%-([\s\S]+?)%>/g
    };

    // When customizing `templateSettings`, if you don't want to define an
    // interpolation, evaluation or escaping regex, we need one that is
    // guaranteed not to match.
    var noMatch = /.^/;

    // Certain characters need to be escaped so that they can be put into a
    // string literal.
    var escapes = {
        '\\': '\\',
        "'": "'",
        'r': '\r',
        'n': '\n',
        't': '\t',
        'u2028': '\u2028',
        'u2029': '\u2029'
    };

    for (var p in escapes) escapes[escapes[p]] = p;
    var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
    var unescaper = /\\(\\|'|r|n|t|u2028|u2029)/g;

    // Within an interpolation, evaluation, or escaping, remove HTML escaping
    // that had been previously added.
    var unescape = function(code) {
        return code.replace(unescaper, function(match, escape) {
            return escapes[escape];
        });
    };

    // JavaScript micro-templating, similar to John Resig's implementation.
    // Underscore templating handles arbitrary delimiters, preserves whitespace,
    // and correctly escapes quotes within interpolated code.
    _.template = function(text, data, settings) {
        settings = _.defaults(settings || {}, _.templateSettings);

        // Compile the template source, taking care to escape characters that
        // cannot be included in a string literal and then unescape them in code
        // blocks.
        var source = "__p+='" + text
            .replace(escaper, function(match) {
                return '\\' + escapes[match];
            })
            .replace(settings.escape || noMatch, function(match, code) {
                return "'+\n_.escape(" + unescape(code) + ")+\n'";
            })
            .replace(settings.interpolate || noMatch, function(match, code) {
                return "'+\n(" + unescape(code) + ")+\n'";
            })
            .replace(settings.evaluate || noMatch, function(match, code) {
                return "';\n" + unescape(code) + "\n;__p+='";
            }) + "';\n";

        // If a variable is not specified, place data values in local scope.
        if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';

        source = "var __p='';" +
            "var print=function(){__p+=Array.prototype.join.call(arguments, '')};\n" +
            source + "return __p;\n";

        var render = new Function(settings.variable || 'obj', '_', source);
        if (data) return render(data, _);
        var template = function(data) {
            return render.call(this, data, _);
        };

        // Provide the compiled function source as a convenience for build time
        // precompilation.
        template.source = 'function(' + (settings.variable || 'obj') + '){\n' +
            source + '}';

        return template;
    };

    // Add a "chain" function, which will delegate to the wrapper.
    _.chain = function(obj) {
        return _(obj).chain();
    };

    // The OOP Wrapper
    // ---------------

    // If Underscore is called as a function, it returns a wrapped object that
    // can be used OO-style. This wrapper holds altered versions of all the
    // underscore functions. Wrapped objects may be chained.
    var wrapper = function(obj) { this._wrapped = obj; };

    // Expose `wrapper.prototype` as `_.prototype`
    _.prototype = wrapper.prototype;

    // Helper function to continue chaining intermediate results.
    var result = function(obj, chain) {
        return chain ? _(obj).chain() : obj;
    };

    // A method to easily add functions to the OOP wrapper.
    var addToWrapper = function(name, func) {
        wrapper.prototype[name] = function() {
            var args = slice.call(arguments);
            unshift.call(args, this._wrapped);
            return result(func.apply(_, args), this._chain);
        };
    };

    // Add all of the Underscore functions to the wrapper object.
    _.mixin(_);

    // Add all mutator Array functions to the wrapper.
    each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
        var method = ArrayProto[name];
        wrapper.prototype[name] = function() {
            var wrapped = this._wrapped;
            method.apply(wrapped, arguments);
            var length = wrapped.length;
            if ((name == 'shift' || name == 'splice') && length === 0) delete wrapped[0];
            return result(wrapped, this._chain);
        };
    });

    // Add all accessor Array functions to the wrapper.
    each(['concat', 'join', 'slice'], function(name) {
        var method = ArrayProto[name];
        wrapper.prototype[name] = function() {
            return result(method.apply(this._wrapped, arguments), this._chain);
        };
    });

    // Start chaining a wrapped Underscore object.
    wrapper.prototype.chain = function() {
        this._chain = true;
        return this;
    };

    // Extracts the result from a wrapped and chained object.
    wrapper.prototype.value = function() {
        return this._wrapped;
    };

}).call(this);